Evolution of Nerve Development in Frogs; pp. 84–93
作者:
Gerhard Schlosser,
Gerhard Roth,
期刊:
Brain, Behavior and Evolution
(Karger Available online 1997)
卷期:
Volume 50,
issue 2
页码: 84-93
ISSN:0006-8977
年代: 1997
DOI:10.1159/000316296
出版商: S. Karger AG
关键词: Cranial nerves;Cranial muscles;Nerve development;Rohon-Beard cells;Metamorphosis;Xenopus laevis;Discoglossus pictus;Whole-mount immunohistochemistry
数据来源: Karger
摘要:
The gross anatomical development of the peripheral nervous system (PNS) during embryogenesis and metamorphosis in the frog Discoglossus pictus is described based on whole-mount immunostaining for nerves and muscles. In the head, neurite outgrowth starts with the mandibular ramus of the trigeminal nerve at the tailbud stage. Cranial muscles are innervated as soon as they differentiate, beginning at mid-embryonic stages. During late embryonic stages, the course of the trigeminal and facial nerves becomes greatly distorted and changes again drastically during metamorphosis accompanying the reorganization of the jaw muscles. Two occipital somites and nerves develop transitorily but degenerate at late embryonic stages. The hypoglossal nerve develops by fusion of the first and second spinal nerves and receives a transitory contribution of the third and fourth spinal nerve at embryonic stages. In the trunk, several classes of Rohon-Beard neurites could be identified at embryonic stages, one of which forms intersegmental sensory nerves that prefigure the course of the sensory rami of spinal nerves at later stages. We give detailed schedules of PNS and cranial muscle de-velopment which, in comparison with data on other frog species described in a companion paper, will serve as a basis to evaluate heterochronic shifts during evolution of PNS development in frogs.
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